In general, an air conditioning system for a car selectively passes and heat-exchanges air introduced into the car by a blower unit toward an evaporator in which refrigerant flows or a heater core in which cooling water of an engine flows, and then, distributes cooled or heated air into the car in various directions through air outlets communicating with components mounted inside the car.
Such air conditioning system includes an air filter for preventing introduction of dust contained in the air introduced into the car by the blower unit, various harmful matters such as benzene and toluene exhausted from exhaust gas, or malodor so as to provide a driver or passengers with purified air.
The air filter is formed in such a way that non-woven fabric or filter media of paper material which is folded in zigzag to physically adsorb and filter bacterial corpuscles, harmful compositions or odor compositions using active carbon particles is mounted inside a flat type frame. The air filter is generally mounted at the upstream side of the blower unit or between the blower unit and the evaporator.
However, since the air filter, in fact, is arranged in front of the evaporator which is the root of the malodor, the air filter can remove the malodor contained in the air introduced from the outside, but cannot directly remove a malodor generated from the evaporator itself.
That is, when the air conditioner is operated in sultry weather in the summer season, due to operation of the evaporator, a great deal of condensate water is formed on the surface of the evaporator. Such condensate water is generally discharged to the outside through a drain hole formed on the lower portion of the air conditioning case, but it is impossible to discharge the entire amount of the condensate water through the drain hole due to surface tension, so that residual condensate water exists in the air conditioning case or the core of the evaporator and acts as a nourishing bed for fungi. So, if the air conditioner is continuously operated, the malodor generated from the evaporator is discharged to the inside of the car in itself when the air introduced from the outside by the blower unit passes through the evaporator, so that the driver or the passengers may feel severe unpleasantness.
Furthermore, since temperature of the surface of the evaporator is rapidly increased when the air conditioner stops the flourishing operation, bacteria and germs act and propagate more lively due to the condensate water remaining in the evaporator. So, when the air conditioner is reoperated, the malodor is introduced into the inside of the car, and air cleanness inside the car is greatly reduced.
Particularly, since the air filter is fixed at its installation place with no change of position and always exposed to the air blown from the blower unit, when a pre-determined period of time is passed, the odor composition is adsorbed and gathered into fine pores of active carbon and reaches saturation, whereby adsorptive force of the filter is gradually reduced and the odor composition adsorbed in a high temperature state is partially discharged to the inside of the car, so that the inside of the car cannot keep the agreeable environment.
Therefore, since the filter must be periodically replaced with a new one when a pre-determined period of time is passed, the conventional air conditioning system has several disadvantages in that it causes inconvenience in use and expensive maintenance costs due to a frequent replacement of the filter.
Furthermore, in sultry weather in the summer season, the odor composition of a saturated state stained on the surface of the filter is separated from the filter by the outside air of high temperature introduced into the car and generates the malodor.
Meanwhile, unexamined Japanese Patent Publication No. 2001-163049 discloses an air conditioning system for a car with an air filter in the vicinity of an air mixing part for mixing air passing through an evaporator and a heater core.
FIG. 1 schematically shows an air conditioning system for the car.
As shown in FIG. 1, the air conditioning system includes: a cool air channel C mounted between an evaporator 101 and a heater core 102 spaced apart from each other at a predetermined distance and arranged in order inside an air conditioning case 100, the cool air passageway C bypassing the heater core; and a temperature door 106 for selectively controlling the degree of opening of a hot air passageway H in front of the heater core and for controlling temperature of the air discharged to the inside of the car through air outlets 103, 104 and 105 communicating with built-in components of the car according to the degree of opening. Here, a space M formed at the downstream side of the temperature door 106 and the heater core 102 is an air mixing part for supplying air of uniform temperature to the inside the car through the air outlets 103, 104 and 105 after properly mixing the cool air passing through the cool air passageway C and the hot air passing through the hot air passageway H.
An air filter 108, which has the structure described above, is inclinedly mounted in a boundary zone between the air mixing part M and a tail wind chamber 107 in such a way as to stop an entrance of the tail wind chamber 107.
The prior art can effectively remove the air passing through the evaporator 101 and dust and malodor contained in the air by the air filter 108, and cause ventilation resistance to improve air-mixing capacity.
However, as described above, since the air filter 108 is fixed on the air passageway always exposed to the air, the prior art may cause ill effects due to limitation in adsorptive force of the filter when the predetermined period of time is passed, and requires lots of maintenance costs due to the periodic replacement cycle of the filter.